1. Field of the Invention
The invention relates to an illumination device, more particularly to an illumination device for plants.
2. Description of the Related Art
With extreme variations of climate, many areas in the world will not be suitable for growth of plants, such as paddy rice and greens, such that people in these areas are to be short of food provisions. In view of this, “plant factories” have been developed in many countries. In the plant factories, an isolated room without dust is provided for plants to be planted, and water and nutrients are sufficiently supplied to the plants in the isolated room under suitable growth conditions, such as illumination and humidity. It is noted that illumination is one of most important growth conditions for plants. For example, illumination with different wavelengths may result in different influences for each plant. Moreover, duration of illumination may influence a growth speed of plants and a sweetness-degree of fruits.
Therefore, it is desired to design an illumination device for plants that is capable of generating illumination conforming to illumination requirements for each plant at different growth stages.